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1
Mamedov, N. V., A. S. Rohmanenkov, and A. A. Solodovnikov. "Magnetic field influence on the Penning discharge characteristics." Journal of Physics: Conference Series 2064, no. 1 (November 1, 2021): 012039. http://dx.doi.org/10.1088/1742-6596/2064/1/012039.
Повний текст джерелаАнотація:
Abstract In this work characteristics of pulsed penning ion source for miniature linear accelerators was investigated by experimental measurements and PIC (Particle-In-Cell) simulations. The paper presents dependences of the discharge current and extracted current on intensities of the uniform magnetic field for different pressure. Also, typical examples of the current pulse waveforms obtained by PIC simulation and experiment for different magnetic field are presented. The simulated electron and ion distributions inside discharge gap give qualitative explanation of the experimentally observed fluctuations in current pulses. These current fluctuations arise as a result of the violation of the electric field axial symmetry due to the electron spoke movement of the towards the anode.
2
Zhang Jun, 张军, 靳振兴 Jin Zhenxing, 张点 Zhang Dian, 杨建华 Yang Jianhua, 舒挺 Shu Ting, 钟辉煌 Zhong Huihuang, and 周生岳 Zhou Shengyue. "4.8 MJ magnetic field excitation source using pulse width modulation technique." High Power Laser and Particle Beams 22, no. 6 (2010): 1323–26. http://dx.doi.org/10.3788/hplpb20102206.1323.
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DÖRR, M., D. ECKERT, H. ESCHRIG, F. FISCHER, P. FULDE, R. GROESSINGER, W. GRÜNBERGER, et al. "THE DRESDEN 100 T/10 ms PROJECT: A HIGH MAGNETIC FIELD FACILITY AT AN IR-FEL." International Journal of Modern Physics B 16, no. 20n22 (August 30, 2002): 3397. http://dx.doi.org/10.1142/s0217979202014541.
Повний текст джерелаАнотація:
We have proposed to build a 100 T/10 ms, 70 T/100 ms, 60 T/1 s pulsed field user facility with a 50 MJ capacitor bank at the Forschungszentrum Rossendorf near Dresden. This would provide the appealing possibility to have access to Zeeman energies in the energy range of the infrared free-electron-lasers (5 μm to 150 μm; 2 ps; cw; > 10 W) now under construction at the radiation source ELBE (superconducting electron linear accelerator; 40 MeV; 1 mA; 2 ps; cw) in Rossendorf. The work is accompanied by computer simulations of the planned coil systems, of the power supply, and by the development of high-strength conductors aiming at a tensile strength of about 1.5 GPa at σ ≈ σ Cu/2 (microcomposite CuAg alloys and Cu-steel macro compounds). With a view of gaining experience in the construction and operation of pulsed magnets, a pilot pulsed field laboratory was established at the Institute of Solid State and Materials Research Dresden (IFW Dresden). The laboratory includes short pulse magnets with peak field up to 60 T in a 24 mm bore and a rise time of about 10 ms (coil from NHMFL, Tallahassee), and a 40 T long pulse magnet with 24 mm bore and rise time of about 80 ms (coil from METIS, Leuven). The repetition rate of 20 min between pulses is limited by the cooling time of the coils. The coils are energized by a 1 MJ, 10 kV capacitor bank with some special features. With this set-up measurements of magnetization and magnetotransport on 4f-electron systems, for example RECu2, have been out in the temperature range of 1.5 to 300 K and at fields up to 52 T using high precision pick-up coils.
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Espina-Hernández, J. H., Roland Grössinger, Reiko Sato Turtelli, and J. M. Hallen. "A New Measuring System for Determining the Magnetic Viscosity in Permanent Magnets." Advanced Materials Research 68 (April 2009): 12–20. http://dx.doi.org/10.4028/www.scientific.net/amr.68.12.
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A new system for measuring magnetic viscosity in bulk hard magnetic materials base on a pulsed field method is presented. After the magnetizing field pulse, the stray field of the sample, which is proportional to the magnetic moment, is measured with a compensated set of two Hall probes. The set of Hall probes is driven with an AC voltage source and the Hall voltage is detected using a lock-in amplifier. By this method the system is able to measure the time dependence of the magnetization (viscosity). The magnetic viscosity coefficient (S) is obtained through a linear fitting of the magnetization decay versus ln t. Two typical Nd-Fe-B samples were measured and good agreement with the results from the traditional viscosity experiment was obtained.
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Fitak, Robert R., Eleanor M. Caves, and Sönke Johnsen. "Orientation in Pill Bugs: An Interdisciplinary Activity to Engage Students in Concepts of Biology, Physics & Circular Statistics." American Biology Teacher 80, no. 8 (October 1, 2018): 608–18. http://dx.doi.org/10.1525/abt.2018.80.8.608.
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We present a novel laboratory activity to introduce students to experimental approaches often used by biologists to study orientation in animals. We first provide an overview of the current understanding of magnetoreception – the ability of some organisms to sense magnetic fields. We then outline an exercise that uses common pill bugs (Armadillidium vulgare) to examine whether a pulsed magnetic field affects their directional preference. The first part of the experiment includes the construction and visual testing of a pulse magnetizer built using low-cost and easily obtainable materials. Afterward, students examine the orientation of pill bugs both before and after being subjected to a magnetic pulse. Finally, students analyze their results with circular statistics using the open-source R coding platform, providing them experience in coding languages and statistical analysis. The interdisciplinary and biophysical nature of this experiment engages students in concepts of electromagnetic induction, magnetism, animal behavior, and statistics.
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Abedi-Varaki, Mehdi. "Effect of obliquely external magnetic field on the intense laser pulse propagating in plasma medium." International Journal of Modern Physics B 34, no. 07 (March 11, 2020): 2050044. http://dx.doi.org/10.1142/s0217979220500447.
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In this paper, self-focusing of intense laser pulse propagating along the obliquely external magnetic field on the collisional magnetoactive plasma by using the perturbation theory have been studied. The wave equation describing the interaction of intense laser pulse with collisional magnetoactive plasma is derived. In addition, employing source-dependent expansion (SDE) method, the analysis of the laser spot-size is discussed. It is shown that with increasing of the angle in obliquely external magnetic field, the spot-size of laser pulse decreases and as a result laser pulse becomes more focused. Furthermore, it is concluded that the self-focusing quality of the laser pulse has been enhanced due to the presence of obliquely external magnetic field in the collisional magnetoactive plasma. Besides, it is seen that with increasing of [Formula: see text], the laser spot-size reduces and subsequently the self-focusing of the laser pulse in plasma enhances. Moreover, it is found that changing the collision effect in the magnetoactive plasma leads to increases of self-focusing properties.
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YANG, YANJU, CHUNLEI CHENG, WENYAO YANG, JIE LI, ZHENGFU CHENG, and XIAOYU ZHANG. "STUDY OF ACOUSTIC SOURCE EXCITED BY PULSED MAGNETIC FIELD." Journal of Mechanics in Medicine and Biology 21, no. 05 (April 14, 2021): 2140008. http://dx.doi.org/10.1142/s021951942140008x.
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In magnetoacoustic tomography with magnetic induction and magnetically mediated thermoacoustic imaging, tissues are exposed to an alternating field, generating magnetoacoustic and thermoacoustic effects in the tissues. This study aimed to investigate the relationship between magnetoacoustic and thermoacoustic effects in a low-conductivity object put in a Gauss-pulsed alternating magnetic field. First, the derivations of the magnetic flux density and electric field strength induced by a Gauss-pulsed current flowing through the coil based on the theory of electromagnetic field were examined. Second, the analytical solution of the magnetic field was studied by simulation. To validate the accuracy of the analytical solution, the analytical solution and the numerical simulation of the magnetic flux density were compared. It shows that the analytical solution coincides with the numerical simulation well. Then, based on the theoretical analysis of the acoustic source generation, numerical studies were conducted to simulate pressures excited by magnetoacoustic and thermoacoustic effects in low-conductivity objects similar to tissues in the Gauss-pulsed magnetic field. The thermoacoustic effect played a leading role in low-conductivity objects placed in the Gauss-pulsed magnetic field, and the magnetoacoustic effect could be ignored. This study provided the theoretical basis for further research on magnetoacoustic tomography with magnetic induction and magnetically mediated thermoacoustic imaging for pathological tissues.
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Kondratenko, I. P., A. N. Karlov, and R. S. Kryshchuk. "CONTROL STRATEGIES TO ELIMINATE HARMONICS IN POWER GENERATION SYSTEMS BASED ON A DOUBLY-FED INDUCTION GENERATOR." Praci Institutu elektrodinamiki Nacionalanoi akademii nauk Ukraini, no. 61 (May 25, 2022): 5–12. http://dx.doi.org/10.15407/publishing2022.61.005.
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The action of high-density pulsed currents (109 A/m2) leads to the appearance of the electro-plastic effect in metal products. It is proposed to use magnetic pulse treatment of nonmagnetic plates by electromagnetic inductors with a U-shaped magnetic circuit for local flow pulsed currents in the nonmagnetic plates. The work aims to establish an influence of a ferromagnetic platform with nonlinear magnetic permeability on pulsed eddy currents and magnetic pressure of nonmagnetic metal plates with different electrical conductivity in modeling magnetic pulse treatment of welded joints to achieve the electro-plastic effect. Numerical simulation of pulsed electromagnetic fields by the finite element method is used. The current calculation in the inductor's winding is performed by solving the equations of the magnetic field and the electric circuit equations for a discrete-time interval. A power source is a capacitor that is charged to a specific voltage. To study the effect of the ferromagnetic platform on eddy currents and forces in a nonmagnetic plate with its different electrical conductivity, the same pulsed current in the inductor's winding is used. The dependence of amplitude values of eddy current density and magnetic pressure on the surfaces of nonmagnetic plates of different electrical conductivity is investigated. The influence of the presence and absence of a ferromagnetic platform and its electrical conductivity and magnetic permeability on the values of eddy currents and magnetic pressure in the nonmagnetic plate have been studied. Ref. 13, fig. 7, table.
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IZUMIDA, SHINJI, SHINGO ONO, ZHENLIN LIU, HIDEYUKI OHTAKE, and NOBUHIKO SARUKURA. "INTENSE THz-RADIATION SOURCES USING SEMICONDUCTORS IRRADIATED WITH FEMTOSECOND LASER PULSES IN A MAGNETIC FIELD." Journal of Nonlinear Optical Physics & Materials 08, no. 01 (March 1999): 71–87. http://dx.doi.org/10.1142/s0218863599000060.
Повний текст джерелаАнотація:
We report significant enhancement of THz radiation from InAs under magnetic field irradiated with femtosecond pulses. The THz-radiation power is significantly enhanced and reaches sub-mW level in a 1.7-T magnetic field with 1.5-W excitation power. The THz-radiation power is related almost quadratically both to the magnetic field and excitation laser power. Furthermore, the radiation spectrum is found to be controlled by the excitation pulsewidth, chirp direction of the excitation pulse, and the magnetic field. Additionally, we have demonstrated a new method to generate THz radiation from a saturable Bragg reflector in a magnetic field.
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Bespalov, Peter A., and Olga N. Savina. "Excitation of the main giant pulses from the Crab pulsar." Monthly Notices of the Royal Astronomical Society 498, no. 2 (August 20, 2020): 2864–70. http://dx.doi.org/10.1093/mnras/staa2520.
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ABSTRACT A model for the source of microwave main giant pulses (GPs) from the Crab pulsar is proposed and partly investigated. Pulse excitation takes place in a relativistic pair plasma with a strong magnetic field through the beam pulse amplifier (BPA) mechanism, in which short noise pulses of a certain type are amplified by energetic electrons at the Cherenkov resonance, even without strong anisotropy in the distribution function. The wave gain is shown to be as high as with an instability of hydrodynamic type, and wave escaping from the excitation region into the pulsar magnetosphere may not involve significant attenuation. The basic parameters of the source which explains the observed characteristics of the GP electromagnetic bursts have been analysed and are consistent with accepted ideas about physical conditions in the pulsar magnetosphere. The BPA mechanism explains the important properties of the GPs, such as the extremely short pulse duration (extreme nanoshots), the extremely high brightness temperature of the radiation source, the formation of radiation in a wide frequency range, and the possibility of radiation reaching the periphery of the pulsar magnetosphere.
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Miranda, R. M., B. Tomás, T. G. Santos, and N. Fernandes. "Magnetic pulse welding on the cutting edge of industrial applications." Soldagem & Inspeção 19, no. 1 (March 2014): 69–81. http://dx.doi.org/10.1590/s0104-92242014000100009.
Повний текст джерелаАнотація:
Magnetic Pulse Welding (MPW) applies the electromagnetic principles postulated in the XIXth century and later demonstrated. In recent years the process has been developed to meet highly demanding market needs involving dissimilar material joining, specially involving difficult-to-weld materials. It is a very high speed joining process that uses an electromagnetic force to accelerate one material against the other, resulting in a solid state weld with no external heat source and no thermal distortions. A high power source, the capacitor, a discharge switch and a coil constitute the minimum equipment necessary for this process. A high intensity current flowing through a coil near an electrically conductive material, locally produce an intense magnetic field that generates eddy currents in the flyer according to Lenz law. The induced electromotive force gives rise to a current whose magnetic field opposes the original change in magnetic flux. The effect of this secondary current moving in the primary magnetic field is the generation of a Lorentz force, which accelerates the flyer at a very high speed. If a piece of material is placed in the trajectory of the flyer, the impact will produce an atomic bond in a solid state weld. This paper discusses the fundamentals of the process in terms of phenomenology and analytical modeling and numerical simulation. Recent industrial applications are presented in terms of materials, joint configurations and real examples as well as advantages and disadvantages of the process.
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Takahashi, Miwako, Ken-ichi Ohshima, and Masatoshi Arai. "A single-crystal time-of-flight neutron diffractometer at a spallation neutron source." Journal of Applied Crystallography 40, no. 4 (July 13, 2007): 799–807. http://dx.doi.org/10.1107/s0021889807023059.
Повний текст джерелаАнотація:
A single-crystal diffractometer using the time-of-flight (TOF) Laue technique had been operated for studies of structural and magnetic disorder and phase transitions in alloys and magnetic materials at the pulsed spallation neutron source facility of the KEK Neutron Science Laboratory (KENS). In various sample environments, the diffractometer has demonstrated its usefulness in measurements of diffuse scattering for studying local structures, and in surveys of reciprocal space for studying phase transitions and incommensurate structures under the conditions of varying temperature and magnetic field. Particular emphasis is placed on the fact that though the instrument did not receive high-flux neutrons for long wavelengths suitable for the studies of magnetic scattering, it gave good results on the observations of magnetic diffuse scattering and superlattice reflections. Remarks and future tasks of the TOF Laue technique are discussed in relation to the asymmetric pulse shape, separation of the inelastic scattering, and dependence of data correction on the sample quality.
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Li, Huan, Hong Fa Ding, and Hou Xiu Xiao. "A Repeated Pulsed High Magnetic Field Generator for Frequency-Tunable Terahertz Sources." Advanced Materials Research 516-517 (May 2012): 1897–901. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.1897.
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This paper presents a Repeated Pulsed High Magnetic Field (RPHMF) generator for frequency-tunable terahertz sources, which mainly consists of a charging power supply, a capacitor bank, a discharging switch, a bitter magnet and other facilities. The four thyristors (80 mm, 4 kV) in series with a self-supplied gate driver are taken as the discharge switch which can be triggered when the high voltage capacitor C was charged to 300 V. Meanwhile, a bitter magnet with fast heat dissipation was designed and fabricated. According to the experiment, the designed system has a pulse repetition frequency of 0.1 Hz with a maximum magnetic field of 9 T.
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Budnarowska, Magdalena, and Jerzy Mizeraczyk. "Temporal and Spatial Development of the EM Field in a Shielding Enclosure with Aperture after Transient Interference Caused by a Subnanosecond High-Energy EM Plane Wave Pulse." Energies 14, no. 13 (June 28, 2021): 3884. http://dx.doi.org/10.3390/en14133884.
Повний текст джерелаАнотація:
A proper assessment of the shielding effectiveness of an enclosure with aperture under subnanosecond transient interference requires a better understanding of the coupling and development mechanisms of the EM field induced inside the enclosure. In this paper, the results of a numerical study of the temporal and spatial development of the electromagnetic (EM) field in a shielding enclosure with aperture after transient interference caused by a subnanosecond high-energy EM plane wave pulse are presented. The interference pulse had Gaussian distribution of the electric and magnetic fields with amplitudes of 106 V/m and 2.68·103 A/m, respectively. The maximum pulse power density was 2.68 GW/m2. The novelty of this study was 2D and 3D images, which visualized the temporal and spatial build-up of electric and magnetic fields in the shielding enclosure within 90 ns after the transient interference. This is 58 times longer than the time needed by any EM wave to travel the distance between the front and rear walls of the enclosure. The presented images, showing the EM field morphology over a relatively long period of time, were crucial for understanding the EM field build-up process inside the shielding enclosure with aperture. They revealed the existence of two unknown phases of the EM field build-up in the enclosure with aperture. We call these two phases the wave phase and the interference phase. In the wave phase, the EM field is generated in the form of so-called primary and secondary wave pulses, traveling towards the enclosure rear wall. In the interference phase, the EM field has the form of temporally and spatially varying pulse-like interference (size-limited) patterns of the associated electric and magnetic fields. The EM field induced in the enclosure is long-lasting compared to the interference pulse duration. The amplitudes of the electric and magnetic fields decreased about threefold in 5 ns and 30-fold in 90 ns, thus exhibiting a severe EM hazard for much longer than the external interference duration. For a long period of time, the highest EM field amplitudes would change their locations in the enclosure, which makes it difficult to assess the shielding effectiveness on the basis of classical definitions. The existence of the long-lasting temporally and spatially varying EM field induced in the enclosure with aperture by the subnanosecond transient interference, visualized in detail in this paper, confirms that a new definition and measurement methods of shielding effectiveness under transient conditions are needed. The obtained results provide a source of data that can be useful when working on the introduction of time-domain parameters to evaluate the transient shielding effectiveness in the case of the ultrashort EM interference.
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Mühle, C., U. Ratzinger, G. Jöst, K. Leible, S. Schennach, and B. H. Wolf. "Pulsed magnetic field‐electron cyclotron resonance ion source operation." Review of Scientific Instruments 67, no. 3 (March 1996): 1331–33. http://dx.doi.org/10.1063/1.1146710.
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Zhou, Y. Z., C. Y. Zheng, Z. J. Liu, and L. H. Cao. "Weibel instability induced by kinetic stimulated Raman scattering in unmagnetized and magnetized plasmas." Plasma Physics and Controlled Fusion 64, no. 4 (February 15, 2022): 045009. http://dx.doi.org/10.1088/1361-6587/ac4bcf.
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Abstract The kinetic stimulated Raman scattering (SRS) is found to result in significant Weibel-generated magnetic fields via 2D particle-in-cell simulations. During the high-intensity laser pulse, the daughter electron plasma waves of SRS heat the electrons effectively and lead to anisotropy in the velocity space. This anisotropy results in the development of a quasi-static magnetic field near the laser speckle, and the growth rate has been discussed. The results show that the kinetic SRS can lead to an averaged magnetic field of more than 10 T, which can be an important magnetic field source in laser-plasma experiments. Besides, the energy of the Weibel-field undergoes an oscillatory rise with the SRS bursts and can be stable after cutting off the laser. Moreover, in the magnetized plasmas, the application of a longitudinal magnetic field enhances the SRS, but interestingly, it significantly reduces the growth rate of Weibel instability. Simulation results also indicate that a small transverse magnetic field can evidently change the motion of the hot electrons, which dramatically destroys the symmetry of the SRS and the Weibel-generated magnetic fields.
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Fujimoto, Junichi, Tsukasa Hori, Tatsuya Yanagida, and Hakaru Mizoguchi. "Development of Laser-Produced Tin Plasma-Based EUV Light Source Technology for HVM EUV Lithography." Physics Research International 2012 (September 5, 2012): 1–11. http://dx.doi.org/10.1155/2012/249495.
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Since 2002, we have been developing a carbon dioxide (CO2) laser-produced tin (Sn) plasma (LPP) extreme ultraviolet (EUV) light source, which is the most promising solution because of the 13.5 nm wavelength high power (>200 W) light source for high volume manufacturing. EUV lithography is used for its high efficiency, power scalability, and spatial freedom around plasma. We believe that the LPP scheme is the most feasible candidate for the EUV light source for industrial use. We have several engineering data from our test tools, which include 93% Sn ionization rate, 98% Sn debris mitigation by a magnetic field, and 68% CO2 laser energy absorption rate. The way of dispersion of Sn by prepulse laser is key to improve conversion efficiency (CE). We focus on prepulsed laser pulsed duration. When we have optimized pulse duration from nanosecond to picosecond, we have obtained maximum 4.7% CE (CO2 laser to EUV; our previous data was 3.8%) at 2 mJ EUV pulse energy. Based on these data we are developing our first light source as our product: “GL200E.” The latest data and the overview of EUV light source for the industrial EUV lithography are reviewed in this paper.
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Sun, Xiaoya, Tsutomu Yamada, and Yasushi Takemura. "Output Characteristics and Circuit Modeling of Wiegand Sensor." Sensors 19, no. 13 (July 7, 2019): 2991. http://dx.doi.org/10.3390/s19132991.
Повний текст джерелаАнотація:
A fast magnetization reversal in a twisted FeCoV wire induces a pulse voltage in a pick-up coil wound around a wire. The Wiegand sensor is composed of this magnetic wire and the pick-up coil. As the output pulse voltage does not depend on a changing ratio of the applied magnetic field to switch the magnetization of the wire, the Wiegand sensor is used for to perform rotation and other detections. Recently, the Wiegand sensor has attracted significant attention as a power supply for battery-less operation of electric devices and for energy harvesting. In this study, we propose a concept of obtaining an intrinsic pulse voltage from the Wiegand sensor as its power source, and demonstrate its effectiveness in circuit simulation. The equivalent circuit for the Wiegand sensor is expressed by the intrinsic pulse voltage, internal resistance, and inductance of the pick-up coil. This voltage as a power source and circuit parameters are determined by MATLAB/Simulink simulation. The output voltage calculated using the equivalent circuit of the Wiegand sensor agrees with the experimentally measured results.
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Belyaeva, Irina A., Vladimir Glushchenkov, and A. Y. Pyl'tsin. "Modeling of “Stretching-Over” Static-Dynamic Process." Materials Science Forum 1031 (May 2021): 216–21. http://dx.doi.org/10.4028/www.scientific.net/msf.1031.216.
Повний текст джерелаАнотація:
The article presents the technological scheme of the “stretching-over” hybrid technology, when the workpiece is simultaneously affected by two sources of loading: static and dynamic. It is proposed to use a pulsed magnetic field as a dynamic load. In this case, the tightening punch is equipped with an inductor connected to a magnetic-pulse unit. As a result of computer simulation, the distribution patterns of the stress-strain state in a tight-fitting workpiece were obtained both in the case of a conventional tight-fitting and with the proposed hybrid one. It was found that exposure to a pulsed magnetic field changes the stress-strain state, making it possible to intensify the stretching process.
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Ding, Yingying, Liwei Song, Junyu Qian, Zhe Liu, Pengfei Wang, Yanyan Li, Yujie Peng, Ye Tian, and Yuxin Leng. "A compact platform for efficient generation and single-shot measurement of high-field terahertz wave with a broadband naturally synchronized mid-infrared source." European Physical Journal Applied Physics 93, no. 1 (January 2021): 10501. http://dx.doi.org/10.1051/epjap/2020200177.
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High-field terahertz (THz) wave is a powerful tool for investigating ultrafast dynamics such as the motion of electrons, the vibration of crystal lattices, the precession of spin, etc. In this letter, we demonstrate the generation of intense single-cycle THz pulses from an organic crystal DSTMS (4-N, N-dimethylamino-4'-N'-methyl–stilbazolium 2,4,6–trimethylbenzenesulfonate) via optical rectification. The generated THz field is characterized by single-shot electro-optic sampling with a linearly chirped probe beam. Meanwhile, the spectrum of the infrared pump is broadened to an octave which supports a 1.9-cycle pulse duration. The proposed scheme displays a sophisticated platform of efficient high-field THz generation, single-shot THz measurement, and a broadband mid-infrared source which is naturally synchronized with the THz pulses.
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Lien, Hung-Lin, and Jen-Yuan Chang. "Magnetic Reference Mark in a Linear Positioning System Generated by a Single Wiegand Pulse." Sensors 22, no. 9 (April 21, 2022): 3185. http://dx.doi.org/10.3390/s22093185.
Повний текст джерелаАнотація:
A Wiegand sensor is composed of a strip of Wiegand wire and a pick-up coil. The research presented in this paper examines and characterizes the fast magnetization reversal in a Wiegand wire, which leads to changes in magnetic flux density in its pick-up coil to produce the so-called Wiegand pulse to be used as a reference mark in a linear positioning system. It was observed in this research that the magnitude and duration of the pulse voltage were independent of driving frequency, indicating that Wiegand effect sensors could be ideal for use as zero-speed transducers. The repeatability of the Wiegand pulse was found to vary with different magnetic flux intensities of external magnetic field, as well as the angle between the magnetic induction line and the Wiegand wire. Through calibrated experimental and numerical parametric studies, the mechanism for producing repeatable Wiegand pulses to be used as a reference mark for precision liner positioning systems was revealed, which represents the novelty of this research. On the basis of this mechanism, the optimal design combination of the Wiegand sensor’s position with respect to the magnetization source can be obtained. Utilizing commercially available Wiegand sensors, it was demonstrated in this research that with a Wiegand pulse serving as a magnetic reference mark, positioning repeatability of 0.3 um could be achieved, which is on the same order as optical scales. The work presented in this research has engineering implications as well as offering scientific insights into magnetization mechanisms for generating enough magnetic remanence to produce a Barkhausen jump, resulting in repeatable Wiegand for use as a reference mark in a linear positioning system.
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Gilson, E. P., R. C. Davidson, P. C. Efthimion, J. Z. Gleizer, I. D. Kaganovich, and Ya E. Krasik. "Plasma source development for the NDCX-I and NDCX-II neutralized drift compression experiments." Laser and Particle Beams 30, no. 3 (June 15, 2012): 435–43. http://dx.doi.org/10.1017/s0263034612000328.
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AbstractCompressed ion beams are being studied as a driver for inertial confinement fusion energy and for the creation of matter in the high-energy-density regime. In order to facilitate compression of a positive ion charge bunch longitudinally and transversely beyond the limit determined by the space-charge field of the bunch, a source of charge-neutralizing electrons must be provided. Plasma sources have been developed for the NDCX-I and NDCX-II experimental facilities, both for the 2-m-long, field-free drift regions, and for the small-diameter interior of the multi-Tesla final focus solenoid. Barium titanate based cylinders with a high dielectric coefficient are used to line the wall of the 2-m-long drift region and by applying a 9 kV pulse between the inner and outer surfaces of the cylinders, plasma with a density in the 1010 cm−3 range is formed. Results are presented from experiments using this plasma source on NDCX-I. A compact plasma source 5.1 cm long and 3.8 cm in diameter, also made using the barium titanate based material, has been developed for use in the bore of the final focus solenoid. Plasma generated near the wall of the plasma source will follow the fringing magnetic field lines of the solenoid and help to fill the bore of the magnet with plasma. Improved designs for the barium titanate plasma sources are being considered that use different inner-surface electrode materials and structures, and also use a modified electrical driver employing a spark gap crowbar switch. In addition, plasma source designs using so-called flashboard technology have been developed. In the flashboard plasma source, high density plasma is formed when the applied high voltage pulse causes a series of breakdowns between isolated copper patches aligned in rows along the surface of the 0.2 mm thick flashboard.
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Cooray, Vernon, and and Gerald Cooray. "A Novel Interpretation of the Electromagnetic Fields of Lightning Return Strokes." Atmosphere 10, no. 1 (January 9, 2019): 22. http://dx.doi.org/10.3390/atmos10010022.
Повний текст джерелаАнотація:
Electric and/or magnetic fields are generated by stationary charges, uniformly moving charges and accelerating charges. These field components are described in the literature as static fields, velocity fields (or generalized Coulomb field) and radiation fields (or acceleration fields), respectively. In the literature, the electromagnetic fields generated by lightning return strokes are presented using the field components associated with short dipoles, and in this description the one–to-one association of the electromagnetic field terms with the physical process that gives rise to them is lost. In this paper, we have derived expressions for the electromagnetic fields using field equations associated with accelerating (and moving) charges and separated the resulting fields into static, velocity and radiation fields. The results illustrate how the radiation fields emanating from the lightning channel give rise to field terms varying as and , the velocity fields generating field terms varying as , and the static fields generating field components varying asand . These field components depend explicitly on the speed of propagation of the current pulse. However, the total field does not depend explicitly on the speed of propagation of the current pulse. It is shown that these field components can be combined to generate the field components pertinent to the dipole technique. However, in this conversion process the connection of the field components to the physical processes taking place at the source that generate these fields (i.e. static charges, uniformly moving charges and accelerating charges) is lost.
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King, Andrew, and Jean-Pierre Lasota. "Pulsing and non-pulsing ULXs: the iceberg emerges." Monthly Notices of the Royal Astronomical Society 494, no. 3 (April 8, 2020): 3611–15. http://dx.doi.org/10.1093/mnras/staa930.
Повний текст джерелаАнотація:
ABSTRACT We show that ultraluminous X-ray sources (ULXs) with coherent X-ray pulsing (PULXs) probably have neutron-star spin axes significantly misaligned from their central accretion discs. Scattering in the funnels collimating their emission and producing their apparent super-Eddington luminosities is the most likely origin of the observed correlation between pulse fraction and X-ray photon energy. Pulsing is suppressed in systems with the neutron-star spin closely aligned to the inner disc, explaining why some ULXs show cyclotron features indicating strong magnetic fields, but do not pulse. We suggest that alignment (or conceivably, field suppression through accretion) generally occurs within a fairly short fraction of the ULX lifetime, so that most neutron-star ULXs become unpulsed. As a result we further suggest that almost all ULXs actually have neutron-star accretors, rather than black holes or white dwarfs, reflecting their progenitor high-mass X-ray binary and supersoft X-ray source populations.
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Коробков, С. В., М. Е. Гущин, В. И. Гундорин, И. Ю. Зудин, Н. А. Айдакина, А. В. Стриковский та А. С. Николенко. "Простейшая эрозионная плазменная пушка из коаксиального кабеля с полиэтиленовой изоляцией". Письма в журнал технической физики 45, № 5 (2019): 45. http://dx.doi.org/10.21883/pjtf.2019.05.47398.17619.
Повний текст джерелаАнотація:
Abstract—A compact pulsed plasma generator of simple design made of a coaxial cable with polyethylene insulation has been described. A plasma gun generates a cloud of carbon-hydrogen plasma with an electron density of more than 10^13 cm^–3, including in a magnetic field produced of up to 500 G and also in the presence of the background plasma with a density of about 10^12 cm^–3, which is produced by an independent source. The high resource of the gun and stability of plasma parameters from one pulse to another allows using such a gun in laboratory experiments simulating dynamic processes in space.
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Skvortsov, Arkady A., Danila E. Pshonkin, and Mikhail N. Luk'yanov. "Influence of Constant Magnetic Fields on Defect Formation under Conditions of Heat Shock in Surface Layers of Silicon." Key Engineering Materials 771 (June 2018): 124–29. http://dx.doi.org/10.4028/www.scientific.net/kem.771.124.
Повний текст джерелаАнотація:
The work is devoted to the study of defect formation processes in the near-surface layers of silicon under thermal shock conditions and to the effect of preliminary exposure in a constant magnetic field on this process. As a result of investigations it was established that dislocation half-loops near the local heat source are formed in the near-surface layers of Si (with a depth of up to 30 μm) after a current pulse of density j> 5.1010 A / m2 passing through the metallized film on the silicon surface. In addition, it was found that preliminary exposure of samples in a constant magnetic field leads to an increase in the dislocation density compared to samples not exposed in a magnetic field.
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Mühle, C., U. Ratzinger, W. Bleuel, G. Jöst, K. Leible, S. Schennach, and B. H. Wolf. "Status of the pulsed magnetic field electron cyclotron resonance ion source." Review of Scientific Instruments 65, no. 4 (April 1994): 1078–80. http://dx.doi.org/10.1063/1.1145068.
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Sirenko, M. M., B. M. Gorkunov, S. G. Lvov, and V. V. Lysenko. "Automated Unit for Magnetization of Strong Magnets of Electromagnetic Drives." Metrology and instruments, no. 2 (May 21, 2020): 13–21. http://dx.doi.org/10.33955/2307-2180(2)2020.13-21.
Повний текст джерелаАнотація:
The paper is about the development of an automated unit with optimum energy and mass-dimensional parameters for high-quality magnetization of magnets of electromagnetic drives, while preserving the integrity of their windings.
The authors develop an approach for calculating amplitude and width of magnetization pulse. The authors than estimate the rise time of leading edge of the pulse, with respect to conditions of complete magnetization of the electromagnetic drive’s magnetic conductor and preservation of its excitation winding integrity.
For the formation of the magnetization pulse with given parameters, the authors propose an electronic device, which feedbacks bitween the drive winding and the pulse current source, which provides power to the inductor winding.
The authors propose a method of the inductor magnetic system synthesis by criteria of: given magnetic field strength in inductor’s operating volume; power supply unit minimal dimensions and it power consumption while magnetizing. The final result is obtaining cross-section profile of the inductor electrical coil with certain dimensions and number of winding’s turns of a wire of certain diameter.
In order to optimize the mass, size, magnetic and energy parameters of the inductor, the authors solve a problem of synthesizing its magnetic system in way of calculating the parameters of the magnetic field for operating volume of the inductor. It is determined by the characteristic overall dimensions of the NZTB type electromagnetic drives (brakes, 0.2 m in diameter), which were subject to magnetization in a field with strength of at least 400 A/m. The result is the determination of geometrical parameters and the cross-section profile of the inductor electrical coil. This profile ensures the uniformity of the magnetic field when magnetizing the electromagnetic drive of given overall dimensions.
On the basis of all these results, the authors develop the functional scheme of the automated unit and propose a structure of a panel for monitoring and management of devices and units involved.
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Storey, Michelle C., J. G. Greenhill, and T. Kotani. "Investigating Pulse Morphology in GX 1+4." Publications of the Astronomical Society of Australia 15, no. 2 (1998): 217–21. http://dx.doi.org/10.1071/as98217.
Повний текст джерелаАнотація:
AbstractObservational and theoretical evidence points to the existence of an unusually high magnetic field on GX 1+4. The pulsar is thus an ideal laboratory for studying two-photon cyclotron emission, an important source of photons of frequency significantly less than the cyclotron frequency in X-ray pulsars. Low-frequency approximations to the two-photon cyclotron emission transition probabilities are derived. These are used to calculate the theoretical opening angle of the double-humped pulse shape predicted by the two-photon cyclotron emission model. The theoretical pulse shape, incorporating the effects of gravitational light bending, is compared with observations of GX 1+4. Observed light curves have opening angles consistent with the theoretically predicted maximum value.
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DORRANIAN, DAVOUD, MAHMOOD GHORANNEVISS, MIKHAIL STARODUBTSEV, NOBORU YUGAMI, and YASUSHI NISHIDA. "Microwave emission from TW-100 fs laser irradiation of gas jet." Laser and Particle Beams 23, no. 4 (October 2005): 583–96. http://dx.doi.org/10.1017/s0263034605060052.
Повний текст джерелаАнотація:
A new kind of high power tunable microwave radiation source is studied theoretically and experimentally. Following the previous works presented by Dorranian et al. (2003, 2004) in this paper more details about the radiation is presented. The theory of the radiation is developed to calculate the radiation spatial distribution, and more discussion on radiation behavior and characteristics is done. In this radiation scheme, a part of large amplitude electrostatic plasma wake, generated by an intense laser pulse or a relativistic electron bunch, are converted to electromagnetic oscillations by applying a modest dc magnetic field perpendicular to the wake propagation direction. A direct one-dimensional (1D) analytic procedure for calculating the magnetized plasma wake equations is developed and the properties of the radiation are investigated theoretically. The effects of the ramp plasma-vacuum boundary in coupling the radiation from plasma to vacuum is noticed and solved by employing a gas jet flow to generate a sharp boundary. Wakefield is excited by TW-100 fs Ti:sapphire laser beam operating at 800 nm wavelength. The neutral density of gas jet flow is measured with a Mach-Zehnder interferometer. The frequency of the emitted radiation with the pulse width of 200 ps (detection limitation) is in the millimeter wave range. Radiation is polarized perpendicularly to the dc magnetic field lines and propagates in the forward direction and normal direction with respect to the laser pulse propagation direction, both perpendiculars to the direction of the applied magnetic field. Intensity of the radiation in different plasma densities and different magnetic field strengths has been observed.
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Sampaio, Edson E. S. "Electromagnetic fields at the sea bottom induced by a line of immersed electric dipoles." Anais da Academia Brasileira de Ciências 83, no. 3 (September 2011): 835–61. http://dx.doi.org/10.1590/s0001-37652011000300007.
Повний текст джерелаАнотація:
The analysis of electromagnetic fields caused by alternate or transient electric currents flowing along a cable in sea water has several applications. It supports the interpretation of electromagnetic geophysical data and safety procedures against the threat of sea mines. The approach to the problem employs a magnetic vector potential in the frequency domain due to a pulse source electric dipole, and performs Laplace and Hankel transforms and integration along the cable, to describe the variation of the magnetic induction field due to an electric dipole of finite length. The result is applicable to shallow or deep sea water environments, adaptable to any transmitting current waveform and useful for wave-field separation. The prospects relate to a horizontal receiving coil at the sea bottom and simulate: a minesweeper campaign with a current source at the sea surface or a geophysical survey with a current source close to the sea floor. Therefore, the present analysis may serve: to define parameters in counter-sweeping of submarine mines; to map the conductivity of sediments under shallow waters for the prevention and control of contamination; and as a first approach in the characterization of offshore mineral and oil economic deposits.
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Li, Jie, Yi Liu, Xi Li, Pan Dong, Feixiang Liu, Yutong Xie, Liansheng Xia, Jidong Long, and Linwen Zhang. "Characteristics of pulsed nanosecond discharge excited by compact solid-state pulse forming line at atmospheric pressure air." Journal of Physics D: Applied Physics 55, no. 14 (January 5, 2022): 145203. http://dx.doi.org/10.1088/1361-6463/ac3e2a.
Повний текст джерелаАнотація:
Abstract Non-equilibrium plasma is a promising technology for the generation of ozone and removal of exhausted fuel gases. However, applications of non-equilibrium plasma are restricted by energy utilization efficiency in many industry fields. Discharge excited by nanosecond pulsed power is regarded as one of the most efficient methods. In this study, a compact five stages stacked Blumlein pulse forming line and photoconductive semiconductor switches-based power source was introduced to generate pulsed plasma. This compact source could achieve over 50 kV with 10.1 ns pulse width and 4.8 ns pulse rising time. Coaxial cylindrical reactor was employed to generate a pulsed streamer discharge driven by the nanosecond pulsed source in atmospheric pressure air. Electrical parameters of the streamer discharge have been obtained in this study, the instantaneous power dissipation exceeds 8 MW and the average energy consumption of each pulse exceeds 56 mJ. Experiments of high speed photography have been conducted to observe the evolution process. It can be found that streamer heads start from the central wire electrode and then head to the grounded cylinder electrode in all radial direction of the coaxial electrode. Triple wire-to-cylinder electrodes discharge shows that all the three coaxial discharges develop synchronously and symmetrically, which shows that is capable of generating large volume non-equilibrium diffusive streamer discharge plasma.
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Andre, Thomas, Julien Angot, Maud Baylac, Pierre Olivier Dumont, Thierry Lamy, Patrick Sole, Thomas Thuillier, Francois Debray, Ivan Izotov, and Vadim Skalyga. "Status and prospects of the 60 GHz SEISM ion source." Journal of Physics: Conference Series 2244, no. 1 (April 1, 2022): 012014. http://dx.doi.org/10.1088/1742-6596/2244/1/012014.
Повний текст джерелаАнотація:
Abstract SEISM is a unique ECR ion source operating at a frequency of 60 GHz. The prototype is based on a simple magnetic geometry, the cusp, allowing the use of polyhelix coils (developed with LNCMI, Grenoble) to generate the closed ECR surface at 2.14T. The plasma is sustained by a high intensity HF pulse (up to 300kW). Previous experiments at LNCMI have successfully demonstrated the establishment of the nominal magnetic field and the extraction of ion beams with a current density up to 1 A cm-2. The presence of afterglow peaks was also observed, proving the existence of ion confinement in a CUSP ECR source. An experimental campaign is carried out in 2021 using a new transport line designed to improve the transmission of the beam to the new detectors. Short and long-term research plans are presented to transform this high current density into a high intensity ion beam that can be used for accelerators of the future.
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Azzerboni, B., E. Cardelli, and A. Tellini. "Analysis of the magnetic field distribution in an homopolar generator as a pulse power source of electromagnetic launchers." IEEE Transactions on Magnetics 24, no. 1 (1988): 495–99. http://dx.doi.org/10.1109/20.43965.
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Han, Mingyue, Yang Luo, Ling Tang, Jiabin Gu, Hua Li, Ye Xu, Sida Luo, and LiuHe Li. "Plasma flux and energy enhancement in BP-HiPIMS discharge via auxiliary anode and solenoidal coil." Plasma Sources Science and Technology 30, no. 11 (November 1, 2021): 115002. http://dx.doi.org/10.1088/1361-6595/ac2c8c.
Повний текст джерелаАнотація:
Abstract As an emerging and extraordinary plasma source, the bipolar-pulse high power impulse magnetron sputtering (BP-HiPIMS) has promising prospects and wide industrial applications. In this paper, an effort to optimize the plasma flux and energy in BP-HiPIMS via auxiliary anode and solenoidal coil was made. This novel plasma source contains two types of auxiliary anode voltage (direct current and pulse) and one type of solenoidal coil current (direct current) to synergistically enhance the plasma generation and diffusion by electric field and magnetic field together. Systematic evaluations of discharge characteristics demonstrate that applying auxiliary anode voltage and coil magnetic field effectively contribute to a reduction in delay time of target current onset and increase in peak amplitude of target current, which are beneficial for improving plasma generation and target sputtering. The complex plasma dynamics are diagnosed by Langmuir probe and optical emission spectroscopy, and simulated by particle-in-cell/Monte Carlo collision approach. These comprehensive investigations on plasma parameters demonstrate that the plasma density, emission intensity of the metal ions, substrate current density, and ionization fraction of sputtered target particles have been improved with the increase of coil current. The observations of the increase in excitation temperature T exc of Ar atoms, and more extended high-energy tails in electron energy distribution function curves imply that the plasma can be significantly heated by the auxiliary anode. Combining the simulation results and theoretical model proposed in the last sub-content, the diffusion and transport mechanism of charged-particles in complex electric and magnetic fields are discussed. From the theoretical analysis, the qualitative relation between the plasma density and coil current is well consistent with the measurements of electron density obtained by Langmuir probe. These evidences all support the idea that the plasma flux and energy can be enhanced in BP-HiPIMS discharge via auxiliary anode and solenoidal coil together.
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Han, Mingyue, Yang Luo, Ling Tang, Jiabin Gu, Hua Li, Ye Xu, Sida Luo, and LiuHe Li. "Plasma flux and energy enhancement in BP-HiPIMS discharge via auxiliary anode and solenoidal coil." Plasma Sources Science and Technology 30, no. 11 (November 1, 2021): 115002. http://dx.doi.org/10.1088/1361-6595/ac2c8c.
Повний текст джерелаАнотація:
Abstract As an emerging and extraordinary plasma source, the bipolar-pulse high power impulse magnetron sputtering (BP-HiPIMS) has promising prospects and wide industrial applications. In this paper, an effort to optimize the plasma flux and energy in BP-HiPIMS via auxiliary anode and solenoidal coil was made. This novel plasma source contains two types of auxiliary anode voltage (direct current and pulse) and one type of solenoidal coil current (direct current) to synergistically enhance the plasma generation and diffusion by electric field and magnetic field together. Systematic evaluations of discharge characteristics demonstrate that applying auxiliary anode voltage and coil magnetic field effectively contribute to a reduction in delay time of target current onset and increase in peak amplitude of target current, which are beneficial for improving plasma generation and target sputtering. The complex plasma dynamics are diagnosed by Langmuir probe and optical emission spectroscopy, and simulated by particle-in-cell/Monte Carlo collision approach. These comprehensive investigations on plasma parameters demonstrate that the plasma density, emission intensity of the metal ions, substrate current density, and ionization fraction of sputtered target particles have been improved with the increase of coil current. The observations of the increase in excitation temperature T exc of Ar atoms, and more extended high-energy tails in electron energy distribution function curves imply that the plasma can be significantly heated by the auxiliary anode. Combining the simulation results and theoretical model proposed in the last sub-content, the diffusion and transport mechanism of charged-particles in complex electric and magnetic fields are discussed. From the theoretical analysis, the qualitative relation between the plasma density and coil current is well consistent with the measurements of electron density obtained by Langmuir probe. These evidences all support the idea that the plasma flux and energy can be enhanced in BP-HiPIMS discharge via auxiliary anode and solenoidal coil together.
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Anishchenko, Galina Ottovna, Vladimir Ivanovich Konokhov, and Denis Vladimirovich Lavinsky. "Heat generation in devices for magnetic-pulse processing of materials." Bulletin of the National Technical University «KhPI» Series: Dynamics and Strength of Machines, no. 2 (December 31, 2021): 123–26. http://dx.doi.org/10.20998/2078-9130.2021.2.249735.
Повний текст джерелаАнотація:
The problem of analysis of non-stationary heat generation due to the flow of electric current in devices for magnetic-pulse processing of materials is considered. An analysis of the available information sources led to the conclusion that a large number of studies in this area are devoted to the study of heat transfer processes during technological operations of induction heating. In other technological operations of magnetic-pulse processing of materials, heat release is also significant. In this case, a non-stationary inhomogeneous temperature field can lead to significant temperature deformations. This, in turn, can cause a loss in the performance of the device due to destruction or irreversible deformation. Adequate modeling of non-stationary temperature propagation in this case is an obligatory step in carrying out computational analysis in the process of designing technological devices. A general strategy is proposed for determining the propagation of a non-stationary temperature field in the presence of a non-stationary non-uniform electromagnetic field. The proposed strategy presupposes a general solution of the problems of the propagation of the electromagnetic field and the temperature field within the framework of a unified design scheme. The use of the finite element method is proposed as a numerical method. The finite element method, when used in such problems, allows one to draw up iterative procedures that can be used to take into account the nonlinear effects associated with the influence of temperature on the electro-physical properties of materials. The problem of sequential determination of a non-stationary, non-uniform electromagnetic field and a non-stationary temperature field in composite matrices intended for electromagnetic pressing of powders of super-strong refractory materials is considered. The distribution of some quantitative characteristics of the electromagnetic field, as well as the dependence of temperature on time are presented.
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Oudini, N., A. Bendib, R. Agnello, I. Furno, and F. Taccogna. "Laser photo-detachment combined with Langmuir probe in magnetized electronegative plasma: how the probe size affects the plasma dynamic?" Plasma Sources Science and Technology 30, no. 11 (November 1, 2021): 115005. http://dx.doi.org/10.1088/1361-6595/ac2d53.
Повний текст джерелаАнотація:
Abstract Laser photo-detachment combined with a Langmuir probe (LP) is used to diagnose negative ion properties in electronegative plasmas. The technique relies on the combined use of a laser pulse and an LP. The laser pulse converts negative ions into electron–atom pairs, while the LP tracks the temporal evolution of electron current (laser photo-detachment signal) that is analyzed to retrieve the negative ion density. Although an external magnetic field is frequently used to enhance the negative ion production and extraction, the data analysis often neglects the effects of the magnetic field on the probe current. This work investigates the response of an electronegative plasma to a laser pulse in the presence of an external magnetic field through a two-dimensional particle-in-cell/Monte Carlo collision model. The results show that a low electron density region surrounding the probe, called a flux-tube, can form for a probe size comparable with or larger than the electron Larmor radius. The formation of the flux-tube strongly affects the components of the laser photo-detachment signal, leading to an important oscillation of probe current during the plateau phase, i.e. the amplitude of the AC component of the probe current is in the same magnitude order of the DC component of this current, and an important overshoot in comparison to the current rise. Numerical results are qualitatively compared to measurements obtained from the RAID negative ion source.
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Takahashi, Kazumasa, Masayuki Kuzumoto, Yuki Matsumoto, Toru Sasaki, and Takashi Kikuchi. "Control of current waveform of laser ion source using pulsed magnetic field." Review of Scientific Instruments 91, no. 3 (March 1, 2020): 033310. http://dx.doi.org/10.1063/1.5128633.
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Cao, Thanh-Luu, Tuan-Anh Le, Yaser Hadadian, and Jungwon Yoon. "Theoretical Analysis for Using Pulsed Heating Power in Magnetic Hyperthermia Therapy of Breast Cancer." International Journal of Molecular Sciences 22, no. 16 (August 18, 2021): 8895. http://dx.doi.org/10.3390/ijms22168895.
Повний текст джерелаАнотація:
In magnetic hyperthermia, magnetic nanoparticles (MNPs) are used to generate heat in an alternating magnetic field to destroy cancerous cells. This field can be continuous or pulsed. Although a large amount of research has been devoted to studying the efficiency and side effects of continuous fields, little attention has been paid to the use of pulsed fields. In this simulation study, Fourier’s law and COMSOL software have been utilized to identify the heating power necessary for treating breast cancer under blood flow and metabolism to obtain the optimized condition among the pulsed powers for thermal ablation. The results showed that for small source diameters (not larger than 4 mm), pulsed powers with high duties were more effective than continuous power. Although by increasing the source domain the fraction of damage caused by continuous power reached the damage caused by the pulsed powers, it affected the healthy tissues more (at least two times greater) than the pulsed powers. Pulsed powers with high duty (0.8 and 0.9) showed the optimized condition and the results have been explained based on the Arrhenius equation. Utilizing the pulsed powers for breast cancer treatment can potentially be an efficient approach for treating breast tumors due to requiring lower heating power and minimizing side effects to the healthy tissues.
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Gavrylova, Tetiana, Evgen Chaplygin, and Svitlana Shynderuk. "Application and schemes of induction preliminary heating in magnetic-pulse treatment of metals." Bulletin of the National Technical University «KhPI» Series: New solutions in modern technologies, no. 4 (10) (December 30, 2021): 17–23. http://dx.doi.org/10.20998/2413-4295.2021.04.03.
Повний текст джерелаАнотація:
The features of the processes of magnetic-pulse processing of metals in traditional schemes of technological processes of modern industrial production are highlighted. The work is a brief description of the state, application, and also proposed induction pre-heating schemes in industrial magnetic-pulse processing of metals. A method for increasing the efficiency of performing specified production operations is considered. The use of preheating leads to a significant improvement in the quality of production operations while reducing energy consumption. New directions of magnetic-pulse processing of metals are noted, implying the transformation of the natural repulsive forces of the metal of the processed object into the forces of magnetic-pulse attraction with a decrease in the operating frequencies of the acting fields. A significant decrease in operating frequencies makes it possible not only to go from repulsion to attraction, but also to go from working with ferromagnetic metals to non-ferromagnetic ones. For example, it becomes possible to attract aluminum blanks. Examples of the use of induction heating of metal blanks in modern industry are given. Various devices used for these operations, offered on the modern market, by both domestic and foreign manufacturers, are considered. The physics of Lenz-Joule heat release is described, the result of which is the induction heating of conductors by Foucault currents in the external electromagnetic field of the instrument. Schemes are proposed for the practical implementation of preliminary induction heating during magnetic-pulse processing of metal blanks, allowing the use of both autonomous devices for exciting eddy currents and a stationary connection, for the same purpose, of an additional source of electricity. As a result of the work, the possibility of increasing the efficiency by increasing the plasticity of the metal when heating the workpiece, as well as possible limitations of the described technology associated with an increase in the active resistance of metals with an increase in the Lenz-Joule heat release is noted.
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Erkaev, N. V., V. A. Shaidurov, V. S. Semenov, and H. K. Biernat. "Effects of MHD slow shocks propagating along magnetic flux tubes in a dipole magnetic field." Nonlinear Processes in Geophysics 9, no. 2 (April 30, 2002): 163–72. http://dx.doi.org/10.5194/npg-9-163-2002.
Повний текст джерелаАнотація:
Abstract. Variations of the plasma pressure in a magnetic flux tube can produce MHD waves evolving into shocks. In the case of a low plasma beta, plasma pressure pulses in the magnetic flux tube generate MHD slow shocks propagating along the tube. For converging magnetic field lines, such as in a dipole magnetic field, the cross section of the magnetic flux tube decreases enormously with increasing magnetic field strength. In such a case, the propagation of MHD waves along magnetic flux tubes is rather different from that in the case of uniform magnetic fields. In this paper, the propagation of MHD slow shocks is studied numerically using the ideal MHD equations in an approximation suitable for a thin magnetic flux tube with a low plasma beta. The results obtained in the numerical study show that the jumps in the plasma parameters at the MHD slow shock increase greatly while the shock is propagating in the narrowing magnetic flux tube. The results are applied to the case of the interaction between Jupiter and its satellite Io, the latter being considered as a source of plasma pressure pulses.
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Guang-Li, Huang. "Magnetic Tube Scale and Electron Acceleration from the Fine Structure of Microwave Bursts." International Astronomical Union Colloquium 141 (1993): 279–82. http://dx.doi.org/10.1017/s0252921100029237.
Повний текст джерелаАнотація:
AbstractA typical microwave burst with fine structures (type Hand) observed by the Dwingloo multi-channel spectrometer is proposed as evidence of a magnetic tube with a small scale and acceleration of electron beams with a short time scale at the source. It is predicted from the observations and theory that the average velocity of non-thermal electrons is about 0.1c and the density of the beam is about 104 cm−3. There is a micro-magnetic tube with a scale length of six hundred kilometers at the microwave source. There is also a quasi-periodic (~ 20 ms) evolution of the beam energy, which may be accelerated by tearing modes. The spectrum of the burst can be explained by the non-uniformity of the magnetic field. The evolution of the spectrum during a single pulse may result from the electron cyclotron maser instability. Hence, information from the fine structure of the spectrum of solar radio bursts is very important for understanding the mechanism of solar flares.
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Hellwagner, Johannes, Liam Grunwald, Manuel Ochsner, Daniel Zindel, Beat H. Meier, and Matthias Ernst. "Origin of the residual line width under frequency-switched Lee–Goldburg decoupling in MAS solid-state NMR." Magnetic Resonance 1, no. 1 (February 19, 2020): 13–25. http://dx.doi.org/10.5194/mr-1-13-2020.
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Abstract. Homonuclear decoupling sequences in solid-state nuclear magnetic resonance (NMR) under magic-angle spinning (MAS) show experimentally significantly larger residual line width than expected from Floquet theory to second order. We present an in-depth theoretical and experimental analysis of the origin of the residual line width under decoupling based on frequency-switched Lee–Goldburg (FSLG) sequences. We analyze the effect of experimental pulse-shape errors (e.g., pulse transients and B1-field inhomogeneities) and use a Floquet-theory-based description of higher-order error terms that arise from the interference between the MAS rotation and the pulse sequence. It is shown that the magnitude of the third-order auto term of a single homo- or heteronuclear coupled spin pair is important and leads to significant line broadening under FSLG decoupling. Furthermore, we show the dependence of these third-order error terms on the angle of the effective field with the B0 field. An analysis of second-order cross terms is presented that shows that the influence of three-spin terms is small since they are averaged by the pulse sequence. The importance of the inhomogeneity of the radio-frequency (rf) field is discussed and shown to be the main source of residual line broadening while pulse transients do not seem to play an important role. Experimentally, the influence of the combination of these error terms is shown by using restricted samples and pulse-transient compensation. The results show that all terms are additive but the major contribution to the residual line width comes from the rf-field inhomogeneity for the standard implementation of FSLG sequences, which is significant even for samples with a restricted volume.
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Beason, R., and P. Semm. "Does the avian ophthalmic nerve carry magnetic navigational information?" Journal of Experimental Biology 199, no. 5 (May 1, 1996): 1241–44. http://dx.doi.org/10.1242/jeb.199.5.1241.
Повний текст джерелаАнотація:
The bobolink (Dolichonyx oryzivorus) uses the earth's magnetic field as one source of directional information for its migratory orientation. However, the location and structure of the magnetoreceptors that transduce the magnetic information to the nervous system are unknown. Because treatment with a strong magnetic pulse results in a change in the direction of orientation, one of the receptors is thought to involve a magnetizable material such as magnetite. The effects of the magnetizing treatment can be abolished (i.e. the bird returns to its original orientation) by blocking the ophthalmic branch of the trigeminal nerve, but the ability of the bird to select and maintain a direction is not affected. These results are consistent with the hypothesis that a magnetizable material such as magnetite is part of the magnetoreceptors that are associated with the ophthalmic nerve.
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Tsurutani, B. T., B. Dasgupta, J. K. Arballo, G. S. Lakhina, and J. S. Pickett. "Magnetic field turbulence, electron heating, magnetic holes, proton cyclotron waves, and the onsets of bipolar pulse (electron hole) events: a possible unifying scenario." Nonlinear Processes in Geophysics 10, no. 1/2 (April 30, 2003): 27–35. http://dx.doi.org/10.5194/npg-10-27-2003.
Повний текст джерелаАнотація:
Abstract. Two electron heating events have been identified on 20 May 1996 when Polar was in the polar cap/polar cusp boundary layer. The electron heating events were located within magnetic holes/cavities/bubbles and were accompanied by nonlinear ± 14 nT peak-to-peak (f ~ 0.6 to 0.7 fcp) obliquely propagating proton cyclotron waves. The electrons appear to be heated isotropically. Electric bipolar pulse (electron hole) onset events were also detected within the heating events. We propose a scenario which can link the above phenomena. Nonlinear Alfvén waves, generated through cusp magnetic reconnection, propagate down magnetic field lines and locally heat electrons through the ponderomotive force. The magnetic cavity is created through the diamagnetic effect of the heated electrons. Ion heating also occurs through ponderomotive acceleration (but much less than the electrons) and the protons generate the electromagnetic proton cyclotron waves through the loss cone instability. The obliquely propagating electromagnetic proton cyclotron waves accelerate bi-streaming electrons, which are the source of free energy for the electron holes.
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König, Ole, Felix Fürst, Peter Kretschmar, Ralf Ballhausen, Ekaterina Sokolova-Lapa, Thomas Dauser, Celia Sánchez-Fernández, et al. "NuSTAR observation of GRO J1744–28 at low mass accretion rate." Astronomy & Astrophysics 643 (November 2020): A128. http://dx.doi.org/10.1051/0004-6361/202039064.
Повний текст джерелаАнотація:
Context. Neutron stars in low-mass X-ray binaries are important systems for studying the physics of accretion onto compact objects. The system GRO J1744–28 is particularly interesting as it usually shows clear pulsations as well as X-ray bursts. Additionally, there are claims for a magnetic field of 5 × 1011 G through the detection of a cyclotron resonant scattering feature (CRSF). Aims. We present the spectral analysis of GRO J1744–28 using ∼29 ks of NuSTAR data taken in 2017 February at a low luminosity of 3.2 × 1036 erg s−1 (3−50 keV). Our goal is to study the variability of the source spectrum with pulse phase and to search for the claimed CRSF. Methods. The continuum spectrum was modeled with an absorbed power law with exponential cutoff, and an additional iron line component. We found no obvious indications for a CRSF, and therefore performed a detailed cyclotron line search using statistical methods. We performed this search on pulse phase-averaged spectra and on phase-resolved spectra. Results. GRO J1744–28 was observed in a low-luminosity state. The previously detected Type II X-ray bursts are absent. Clear pulsations at a period of 2.141124(9) Hz are detected. The pulse profile shows an indication of a secondary peak that was not seen at higher flux. The upper limit for the strength of a CRSF in the 3−20 keV band is 0.07 keV (90% CL), lower than the strength of the line found at higher luminosity. Conclusions. The detection of pulsations shows that the source did not enter the “propeller” regime, even though the source flux of 4.15 × 10−10 erg cm−2 s−1 was almost one order of magnitude below the threshold for the propeller regime claimed in previous studies on this source. The transition into the propeller regime in GRO J1744–28 must therefore be below a luminosity of 3.2 × 1036 erg s−1 (3−50 keV), which implies a surface magnetic field ≲2.9 × 1011 G and mass accretion rate ≲1.7 × 1016 g s−1. A change of the CRSF depth as function of luminosity is not unexpected and has been observed in other sources. This result possibly implies a change in emission geometry as function of mass accretion rate to reduce the depth of the line below our detection limit.
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Omelyanenko, M. M., V. V. Borisov, A. M. Donyagin, H. G. Khodzhibagiyan, S. A. Kostromin, A. A. Makarov, and A. V. Shemchuk. "Low-noise pulsed current source for magnetic-field measurements of magnets for accelerators." Physics of Particles and Nuclei Letters 14, no. 1 (January 2017): 219–26. http://dx.doi.org/10.1134/s1547477117010216.
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Oks, E. M., I. G. Brown, M. R. Dickinson, and R. A. MacGill. "Upgrade of a vacuum arc ion source using a strong pulsed magnetic field." Review of Scientific Instruments 67, no. 3 (March 1996): 959–61. http://dx.doi.org/10.1063/1.1146783.
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Prikryl, P., D. B. Muldrew, G. J. Sofko, and J. M. Ruohoniemi. "Solar wind Alfvén waves: a source of pulsed ionospheric convection and atmospheric gravity waves." Annales Geophysicae 23, no. 2 (February 28, 2005): 401–17. http://dx.doi.org/10.5194/angeo-23-401-2005.
Повний текст джерелаАнотація:
Abstract. A case study of medium-scale travelling ionospheric disturbances (TIDs) that are correlated with solar wind Alfvén waves is presented. The HF radar ground-scatter signatures of TIDs caused by atmospheric gravity waves with periods of 20-40min are traced to a source at high latitudes, namely pulsed ionospheric flows (PIFs) due to bursts in the convection electric field and/or the associated ionospheric current fluctuations inferred from ground magnetic field perturbations. The significance of PIFs and TIDs in the context of solar-terrestrial interaction is that Alfvénic fluctuations of the interplanetary magnetic field (IMF) observed in the solar wind plasma streaming from a coronal hole correlate with PIFs and TIDs. The link between the solar wind Alfvén waves and TIDs is corroborated by the ground magnetic field signatures of ionospheric current fluctuations that are associated with the IMF-By oscillations and TIDs. The observed PIFs and the associated negative-to-positive deflections of the ground magnetic field X component are interpreted as ionospheric signatures of magnetic reconnection pulsed by solar wind Alfvén waves at the dayside magnetopause. Although the clarity of the radar line-of-sight velocity data may have been affected by anomalous HF propagation due to intervening TIDs, the application of a pure state filtering technique to analyze the radar data time series reveals a one-to-one correspondence between PIFs, TIDs and solar wind Alfvén waves. The spectra of solar wind and ground magnetic field perturbations are similar to those of PIFs and TIDs. The ground-scatter signatures indicate TID wavelengths, phase velocities and travel times that are consistent with ray tracing, which shows a subset of possible gravity wave group paths that reach the F region from a source in the E region after the wave energy first travel downward to the upper mesosphere where the waves are reflected upward. The observed one-to-one correspondence between the convection electric field bursts and TIDs is consistent with the modeling results for large-scale TIDs by Millward et al. (1993a,b). The correlation with solar wind Alfvén waves points to very direct coupling of energy in the solar wind into the subauroral atmosphere.